/Engine/Plugins/Online/OnlineSubsystemUtils/Source/OnlineSubsystemUtils/Public/SpectatorBeaconState.h
Get an existing reservation for a given spectator
index of reservation, INDEX_NONE otherwise
virtual int32 GetExistingReservation ( const [FUniqueNetIdRepl](API\Runtime\Engine\GameFramework\FUniqueNetIdRepl) & Spectator ) const